Method and apparatus for balancing rotors



April 3, 1951 c. H. LINDENBERG ET-AL 2, ,7

METHOD AND APPARATUS FOR BALANCING ROTQRS Filed Sept. 16, 1947 9 Sheets-Sheet 1 BY Theodore 04790129. W, W

ATmRNEYS' April 3, 1951 c. H. LINDENBERG ET AL METHOD AND APPARATUS FOR BALANCING ROTORS Filed Sept. 16. 1947 9 Sheets-Sheet 2 Ill/IIII/l. I

w W f mm m HM n Z A Zfiur/es/i BY Theodor flnyaro. W, W

April 3, 1951 c. H. LINDENBERG ET AL 2,547,764

METHOD AND APPARATUS FOR BALANCING ROTORS Filed Sept. 16, 1947 9 Sheets-Sheet 3 m s. a m E k m mm a 3.5 @Nfi R H a II. N 1 m 8 9 mwaw 1|. m Ill IMW I IH P. am wg w I W o 2 a z m m 6 3% MM. 0 mm Y m B Ill/ W, 9P7)- M [ATTORNEYS April 3, 1951 c. H. LINDENBERG ETAL 2,547,764

METHOD AND APPARATUS FOR BALANCING ROTORS 9 Sheets-Sheet 4 Filed Sept. 16, 1947 lZar/ksfll ATTORNEYS INV ENTOR Meadow 049mm; W M M April 3, 1951 c. H. LINDENBERG ET AL 2,547,764

METHOD AND APPARATUS FOR BALANCING ROTORS Filed Sept. 16, 1947 9 Sheets-Sheet 5 INVEN 0R5 m .12 a 119 rzzzzw'aflg'ziz April 3, 1951 c. H. LINDENBERG ETAL 2,547,764 METHOD AND APPARATUS FOR BALANCING ROTORS Filed-Sept. 16, 1947 9 Sheets-Sheet 6 INV ENTORS fiarlesbillaawberg F'O RMU LA BY Tfieaobm Ongaro. BY (G+H+F)IAXG KZE ATTORNEYS April 3, 1951 c. H. LINDENBERG ET AL 7 2,547,764 METHOD AND APPARATUS FOR BALANCING ROTORS Filed Sept. 16, 1947 9 Sheets-Sheet 7 INL/ENTORS [bar/es lib/M 1160;

BY Mao/ore 0090/0.

April 3, 1951 c. H. LINDENBERG ET AL 2,547,754

METHOD AND APPARATUS FOR BALANCING ROTORS Filed Sept. 16, 1947 9 Sheets-Sheet a INIfEN TORS (liar/es Ill lndellfiery.

y Theodor? 0/190).

ATTOANEYS April 3, 1951 c. H. LINDENBERG ET AL 2,547,764

METHOD AND APPARATUS FOR BALANCING RQTORS Filed Sept. 16, 1947 9 Sheets-Sheet 9 INYENTORS b mtmies/i 11170911159139.

Fi 40 BY ffieoaa'le Onyara W Mr M,

ATTORNEYS I Patented Apr. 3, 1951 METHOD AND APPARATUS FOR BALANCING ROTORS Charles H. Lindenberg and Theodore Ongaro, Co-

lumbus,'0hio, assignors to Lion Manufacturing Inc., Columbus, Ohio, a corporation of Ohio Application September 16, 1947, Serial No. 774,189

27 Claims.

Our invention relates to method and apparatus for balancing rotors. It has to do, more particularly, with a method and apparatus for balancing rotors under dynamic conditions simulating actual running conditions.

The rotating parts of many machines, herein referred to as rotors, must be balanced in order to prevent excessive vibrations, especially if the speed of rotation is high. The forces resulting from unbalance in the rotor are of two types, namely, that type which results in radial force, or what might be termed single plane unbalance, and that type which results in axial moments or couples and refers to the unbalanced portions at different planes axially of the rotor.

It is common practice at the present time to attempt to overcome the unbalanced radial force or single plane unbalance by means of static or standing balancing. In this operation, the rotor is supported with its axis horizontally disposed on knife edges or free bearings to permit the heavy side to fall or rotate to the bottom. Then weights are applied to the opposite side of the rotor to counterbalance the heavy side. This method is extremely slow, involves cut and try operations and is not accurate for rotors to be used at high speeds. The unbalanced radial force may have a. different effect under running conditions than it does under static conditions and this is especially true if the rotor is a body which flexes or is distorted by centrifugal force during rotation.

To attempt to produce dynamic or running balance after the rotor is balanced statically as above, it is customary to use testing machines which support the rotor so that its'unbalanced axial moments or couples will produce vibrations when it is rotated under simulated running conditions. These machines usually include electric pickups by means of which an attempt is made to locate the angular position of the unbalanced forces and to estimate, by means of the extent of vibration, the amount of weight causing the unbalance. This method cannot be consistent because in any such system of vibration pickup, there is lag between the actual point of the force causing the unbalance and the instant of reaction in the rotating mass. Since this lag varies with the speed, attempts are made to operate the machine near the critical speed of the unbalanced rotor, or speed where the unbalanced forces have their greatest effect, but since this speed is variableand unpredictable, the method becomes a trial and error system at best. 1

There is no prior art method or machine, with which we are familiar, which is capable of ac- -curately and consistently balancing at all speeds any rotatable body to overcome both single plane unbalance or unbalanced radial force and multiplane unbalance or couples occurring as axial moments.

Prior art machines for balancing purposes have usually been difficult to operate, requiring a highly skilled operator to attempt to determine the location and extent of the unbalance. Furthermore, the extent and location of the unbalance is not definitely indicated, requiring a considerable amount of calculation by the operator.

The main object of our invention is to provide a method and machine for accurately and consistently balancing at all speeds of rotation any body to be rotated in use in such a manner as to overcome both unbalanced radial force and axial moments or, in other words, to overcome those unbalanced conditions which prior art methods attempted to overcome by the usual static and dynamic balancing.

Another object of our invention is to provide a method and machine as indicated above wherein the rotor is balanced under conditions simulating actual running conditions to overcome both single plane. and couple types of unbalance. Y

Another object of our invention is to provide a balancing machine wherein the rotor is balanced on the machine under conditions simulating running conditions to overcome both types of unbalance by introducing calibrated equal and opposite forces to the unbalanced forces in the rotor while it is being rotated.

Still another object of our invention is to provide a machine of the type indicated in the preceding paragraph wherein the unbalanced condition of the rotor is not only indicated while it is being rotated on the machine but the rotor is actually brought into balance while on the machine and, therefore, the effect of lag between the instant of vibration and the indication or pickup of such vibration is eliminated.

A further object of our invention is to provide a machine of the type indicated of such a nature that a rotor mounted thereon can be brought into balance with ease and accuracy, the 'machine being so simple and easy to operate that a highly skilled operator is not required and no calibration by the operator is required since the location and amount of weight correction necessary to bring the rotor intobalance will be definitely indicated. 1

According to our invention, we rotate the rotor to be balanced under conditions simulating actual running conditions at various speeds. While the rotor is so rotated, it is brought into actual balance by the use of counterbalance weight which introduces calibrated equal and opposite forces. to the unbalanced forces in the rotor and overcomes such unbalanced forces.

According to our invention, the rotor is so supported during rotation that the radial force or single plane unbalance force is permitted first to exert its greatest effect on the machine assembly and by proper adjustment of a counterbalance weight on such assembly the rotor is brought into balance under running conditions. This step is different from the prior art wherein the single plane unbalance is tested andanattempt is made to correct is under static conditions. The position of the counterbalance weight, on our machine assembly, will indicate the position and amount of counterweight which should be added to or removed from the rotor to overcome the single plane unbalance. Thus, the rotor is brought into balance to overcome the single plane unbalance under running conditions during which such unbalance will have substantially the same eifect as during rotation of the rotor in actual use. This is especially important in the case of a rotor which flexes or becomes distored under centrifugal force. although it is also important where the rotor is a rigid body since even then small unbalanced forces which cannot be detected by the static method become apparent at high speeds.

After the rotor is brought into balance, as indicated above, it is so supported that the axial moment or unbalanced couple force will exert its greatest effect on the machine assembly when the rotor is rotated. The same counterbalance weight on the machine assembly is now adjusted to overcome this type of unbalanced force. The proper adjustment of the weight will bring the rotor into balance on the machine assembly under running conditions. The position of this weight will indicate the amount and position of the counterweight to be added to the rotor to overcome this type of unbalance. When such weight is added to the rotor, the rotor will be in exact balance both as to single plane and. couple efiects.

During both balancing operations, the rotor is actually brought into balance on the machine assembly. Thus, the lag eifect, previously mentioned, will not be present during either operation. Since the rotor is actuallybalanced by adjustment of the counterbalance weight, the necessary correction is accurately indicated and located and no calibration by the operator will be necessary.

By the accompanying drawings we have illustrated the principles of our invention and apparatus by which our method can be performed. In these drawings:

F gure 1 is a side elevational view of a balancmg machine constructed in accordance with our invention.

Filgure 2 is a plan view of the machine of Figure Figure 3 is an end view of the machine of Figures 1 and 2.

Figure 4 is a view taken substantially along lme 4-4 of Figure 3 showing the face of the instrument panel of the machine.

Figure 5 is a sectional view taken. along line 5-5 of Figure 4.

Figure 6 is a face view of the dial! WhlQh in- 4 dicates the relative angular positions of the unbalanced force in the rotating rotor and the counterbalance weights of the machine.

Figures '7 and 8 are views similar to Figure 6 but illustrating the dial as showing two different conditions during the balancing operation.

Figure 9 is a view partially in section taken generally along line 9-9 of Figure 2.

Figure 10 is a transverse sectional view taken along line Ill-AB. of Figure 9 and illustrating cam-actuated contacts for controlling the electric circuit which operates indicating mechanism of the machine that shows where the weight correction should be made on the rotor.

Figure 11 is a face View of the mechanism of Figure 10 showing the parts thereof in different positions from Figure 10.

Figure 12 is a similar view illustrating still different positions of the parts.

Figure 13 is a top view of a portion of the mechanism of Figure 9.

Figure 14 is a transverse sectional view taken substantially along line I l-44 of Figure 2 illustrating one of the bearing structures used for supporting the shaft which is adapted to carry the rotors to be balanced.

Figure 15 is a side view of the bearing structure shown in Figure 14.

Figure 16 is a plan view partly broken away of the bearing structure of Figures 14 and 15.

Figure 17 is a perspective view of the bearing structure.

Figure 18 is a diagrammatic view illustrating the counterbalance weights associated with the rotor and the adjustment of such weights to bring the rotor into balance to overcome single plane unbalance.

Figure 19 is a diagrammatic view illustrating how the rotor supporting shaft is pivoted for os-' cillation or vibration about a pivot so located that the single plane unbalance will be effective to produce such vibration in the single plane bal ancing operation.

Figures 20 to 22, inclusive, are views similar to Figure 19 but illustrating successive steps in the balancing operation.

Figure 23 is a diagrammatic view in perspective illustrating the single plane balancing operation.

Figure 24 is a view similar to Figure 19 but showing the rotor supporting shaft pivoted for vibration about a different pivot so that the unbalanced couple effect will be more pronounced preparatory to the couple balancing operation.

Figures 25 to 2'7, inclusive, are views similar to Figure 24 illustrating successive steps in the couple balancing operation.

Figure 28 is a diagrammatic view in perspective showing the counterbalancing weights associated with a rotor and indicating the principles involved in the couple balancing operation.

Figure 29 is a similar perspective view of a portion of the rotor further illustrating the principles involved in the couple balancing operation.

Figure 30 is a face view of the rotor of Figure 28 showing the counterbalancing weights associated therewith and illustrating diagrammatically how such weights are adjusted in the balancing operation.

Figure 31 is an edge view of the rotor of Figure 30 showing the weights associated therewith.

Figure 32 is a view illustrating the formula involved in the couple balancing operation.

Figure 33 is a schematic view of the operating partly in vertical section illustrating a rotor of the type afifected by air resistance upon rotation, showing it enclosed in a housing mounted on the rotor supporting shaft so that air resistance will be eliminated.

Figure 35 is a vertical sectional view taken along line 3535 of Figure 34.

Figure 36 is a force diagram illustratingthe effect of unbalanced radial force on a rotor.

Figure 37 is an edge view of the rotor of Figure 36 illustrating the plane of the force.

Figure 38 is a diagrammatic view illustrating how the rotor supporting shaft is pivoted so that the unbalanced radial forceis effective to cause vibration or oscillation of the shaft and illustrating how the unbalance is overcome.

Figure 39 is a view similar to Figure 38 but 11-- lustrating how the rotor shaft is pivoted so that the unbalanced axial moments or couple are effective to cause vibration of the shaft.

Figure 40 is a similar view but illustrating the rotor brought into true running balance.

With reference to the drawings, in Figures 1, 2 and 3, we have illustrated generally a machine constructed in accordance with our invention and which can be employed for performing our balancing method. The machine comprises a supporting structure in the form of a base I having supporting standards 2 and 3 at opposite ends. The base I carries a driving mo tor 4 which has a brake 4a associated therewith that is controlled by means of a foot pedal 5. The motor 4 has a drive shaft 6 which carries a pulley l on its outer end that drives a belt 8. The belt 8 is adapted to drive, as will later appear, the rotor supporting shaft 9 which is carried upon the upper ends of the standards 2 and 3.

On the upper end of the standard 2 is a bearing unit while on the upper end of the standard 3 is a bearing unit ll. These two units are identical and a description of one will suffice for both. They serve to confine vibrations of shaft 9, which are produced by unbalanced weight in the rotor to be balanced, to a horizontal plane.

The structure of these bearing units is illustrated best in Figures 14 to 17, inclusive. The bearing structure comprises a horizontally disposed supporting plate |2 which is mounted on the upper end of the standard for transverse reciprocatory movement. This plate rests on a plurality of rollers I3 which are disposed transversely of the plate and which are rotatably mounted in the edges of recesses l4 formed in the top of the standard, as shown best inFigure 16. To limit the movement of the plate I2 and to prevent it from being lifted from the standard, a pair of upstanding bolts l5 are threaded into the bottoms of the recesses Hi. These bolts l5 extend upwardly through a pair of slots l6 which extend at right angles to the rollers I3. Thus, when the plate i2 is moved transversely of the standard, the bolts l5 permit such movement and normally the bolts will not contact the ends of the slots. Washers ii are held in place on the upper. end of bolts l5 by nuts l8 and extend over the edges of the slots iii to prevent upward movement of the plate l2.

The lower half i9 of the bearing structure is formed integral with the plate l2 and extends "upwardly therefrom. The upper'half 28 is secured to the lower half by means of clamping bolts 2| which extend downwardly through alignplate l2 and centrally thereof. provided in the solenoid for normally forcing the plunger 26 upwardly into the socket 21.

8- extends so as to drive the shaft.

. 8 'ing sleeves formed in the two halves-of the bearing. Within the bearing structure formed by the members l9 and 20, a bearing sleeve 22 is disposed. This bearing sleeve has integral trunnions 23 formed on its upper-and lower edges which extend into pivot sockets in members '28 and IS. The sleeve 22 is provided with a bushing 23a which snugly embraces the rotor supporting shaft 9. The sleeve 22 has flattened sides,

as indicated at 24 in Figure 14, so that it can oscillate about the axes of pivots 23 without interfering with the bearing sections l9 and 20. Thus, with this bearing structure, when the plate I2 is released, the entire bearing unit can move transversely and at the same time the sleeve 22, which carries the shaft, can oscillate about the axes of trunnions 23.

In order to lock the plate l2 in position centrally of the standard when it is desired to prevent reciprocation thereof, a solenoid unit 25 is mounted within the standard adjacent the upper end thereof. This'unit has a plunger 26 projecting upwardly through the top of the standard and which is adapted to cooperate with a funnelshaped socket 21 formed in the lower surface of A spring 28 is However, current may be supplied to the solenoid to withdraw the plunger 26 from socket 21 and, therefore; release the plate I2 and the bearing structure which it carries for movement transversely of the standard. It will be noted that since the upper end of the pin 26 is rounded and the socket 21 is funnel-shaped, the plate IE will be exactly centered.

When the machine is being used in the balancing operation, one of the bearing structures will be locked by means of a solenoid While the other will be released. In the locked bearing structure, the sleeve 22 will merely pivot on the trunnions 23. In the unlocked bearing structure, the

sleeve will pivot about the trunnions and simultaneously the plate l2 will reciprocate transversely. The bolts I5 are somewhat smaller in diameter than the width of slots IE5 so as to permitslight sliding of plate |2 of the unlocked :bearing during swinging movement of the shaft on rollers |3 in the direction of theaxes thereof The end of .the shaft 9 adjacent the standard '2 (Figures 1 and 2) extends beyond the standard and carries a pulley 29 around which the belt Since the extent of the swinging movement of this end 'of the shaft is not very great, regardlessof which pivot is locked, the belt- 8 will not be displaced from pulley 29- during such swinging movement. The opposite end of the shaft 9 extends through which the rotor is clamped after it is positioned on the shaft; The members 30 and 3| will cooperate with the hub of the rotor to center the -rotor and clamp it on the shaft.

A guard 32 is preferably associated with the rotor, the lower sections being fastened to the standard 3 and the upper section being hinged to the lower section, as at 33 in Figure 3, such section being.

provided with a handle 34 by means of which it may be swung upwardly to permit positioning of the rotor on the shaft or removal of it therefrom. A safety switch, is, provided on the adjacent parts of the upper and lower guard sections and include contacts 32a and 321) (Fi ure 3) which are separated whenever the guard sections are separated. This switch controls the circuit to motor 4 and, consequently, when the guard is open the rotor cannot be rotated.

Associated with the shaft 9 we provide controllable counterbalanced weights for bringing the rotor into running balance and means for indicating the location of the unbalanced weight in the rotor and for indicating when the rotor is brought into balance by adjustment of the weights. This structure is illustrated best in Figures 9 to 13, inclusive.

It will be noted from Figure 9 that the shaft 9 is provided with a sleeve 35 which surrounds the shaft in spaced relationship thereto but which has an integral collar at its end, adjacent bearing H), which is keyed by means of a pin 31 to the shaft for rotation therewith. Extending from the collar 36 to a point adjacent the bearing II is a sleeve 38 which closely fits the shaft 9. The portion 39 of the sleeve 38 which fits within the sleeve 35 is reduced and is rotatable within the sleeve 35 and relative to shaft 9. This portion 39 is provided with a helical slot 49 with which a pin 4i cooperates, the pin being carried by a collar 42 mounted for axial movement on the outer surface of the sleeve 35. The pin 4i extends through a longitudinal slot 43 formed in the sleeve 35 and, consequently, the collar 42 can move axially of sleeve 35 but cannot rotate independently of such sleeve. It will be apparent that when collar 42 is shifted axially, the sleeve 38 will be rotated by means of pin 4i and helical slot 40. Between the end of sleeve 38 and the collar 36 of sleeve 35 a thrust bearing 44 is provided.

The collar 42 is shifted axially of sleeve 35 by means of a hand lever 45 shown best in Figures 1, 2 and 3. This hand lever is pivoted intermediate its ends, as at 46. (Figure 2), to a support 41 which is supported parallel to the shaft 9 by means of inwardly extending arms 43 and 49 which are bolted, respectively, to the standards 2 and 3. The inner end of the lever 35 carries a yoke 55 which straddles a collar 42a. and is connected thereto by pin and slot connections As shown in Figure 13, collar 42a is rotatably mounted on collar 42 by being disposed in groove 4% thereof. It will be obvious that when the lever 45 is swung about its pivot 45, the collar 42 will be moved axially of the sleeve 35. Consequently, the sleeve 38 will be rotated.

The end of the sleeve 33 which is adjacent the bearing H is provided with a thrust bearing 52 which is disposed between the sleeve 38 and the sleeve 22 of the bearing ll. Disposed on a reduced. portion 53 at this end of sleeve 38 is a cam-carrying sleeve 54. This sleeve 54 is provided with a cam 55 at its extreme end. Between the inner end of sleeve 54 and an enlarged portion 55 of sleeve 38 a pair of weightcarrying collars 51 and 51a are mounted on the portion 53 of sleeve 38 in nested relationship, collar 51 being inside and collar 51a surrounding collar 51. Surrounding the portion 56 and the collar 51a and extending over the sleeve 54 is a weight-adjusting sleeve 55. This sleeve 53 is sp ined, as at 59, to the portion 55 of sleeve 38 and, as at 60, to the sleeve 54. Thus, it can move axially of these members but will not rotate relative thereto. Each of the collars 51 and 51a is provided with radially extending pin or arm 5i which carries a counterbalance weight 52 (Figure 1) on its outer end. To permit the arms 6: to be in the same plane, which is at right angles to the axis of shaft 9, the pin 6| on inner collar 51 extends outwardly through a slot 511) in outer collar 51a, such slot extending sufficiently to permit the required relative movement of arms 5|. Each of the arms 51 extends through a helical slot 63 formed in the sleeve 58. These slots are such that by moving the sleeve 58 axially the weights can, be shifted angularly relative to each other. It will be noted that by means of the sleeve 58, the sleeve 55 is connected to the sleeve 38 for rotation therewith.

The sleeve 58 can be moved axially by means of a hand lever 64 (Figure 2) which is similar to the lever 45 and is pivoted by a pivot 65 to the support 41. The yoke 65 formed on the inner end of this lever is connected by a pin and slot connection 51 to a collar 58a, rotatably mounted on collar 58 carried on sleeve 54 so as to permit free rotation of the collar 58. It will be apparent that movement of lever 64 will move the sleeve 58 axially and will rotate the collars 51 and 51a (Figure 9) and thereby adjust the weights 62 circumferentially relative to each other towards or away from cam 55 which will be the mid-point between arms 6!. Rotation of the sleeve 38 by shifting the collar 42 will cause the sleeve 54 and sleeve 53 to rotate therewith. Thus, the cam 55 will be shifted relative to the shaft 9. However, this adjustment will not disturb the relationship of the cam 55 to the weights 62. This relationship can only be changed by moving the sleeve 58 axially to shift the weights relative to each other and, therefore, relative to the cam 55.

The shaft 9 and associated mechanism serves as the balancing assembly of the machine. For indicating various conditions during the balancing operations with this assembly, we provide indicating mechanism which will now be described.

The dials of this indicating mechanism are shown best in Figures 4 and 5. They are carried by a panel type housing 15 which is carried by a pair of upstanding bars 11 that are attached at their lower ends to a horizontal bar 12 which has one end secured to the standard 2. It will be noted best from Figure 3 that the housing 15 is supported above the level of the balancing assembly parallel to the shaft 9 and facing towards the side of the machine where the control levers 45 and 64 are located. Thus, as. the operator actuates the levers 45 and 64 he can view the instruments carried by the housing 15.

The first instrument shown at the left of Figures 4 and 5 andcarried by housing 15 is that indicated by the numeral 13 which will indicate the position of the force center of the counterbalancing weights 52 relative to the shaft 9 and also the position of the excess weight of the rotor, causing the unbalance, relative to the controllable weights. This instrument includes a dial 14 which is driven upon rotation of the shaft 9. The dial shaft 15 is driven by bevel pinions 15 which are driven by a flexible shaft 11, as shown best in Figure 5. This shaft 11 extends through a flexible conduit 18 to the end of shaft 9 (Figures 1, 2 and 3) to which it is suitably coupled. Behind the dial 14 an inner luminous tube 19 and an outer luminous tube are mounted in a fixed position and cooperates, respectively, with the spaced openings 8| and 82 which are in the form of arrows as shown in Figure 4. It will be apparent from the description of the electric circuit, which follows, that suitable pick-ups or electric switches are provided for independently illuminating the two tubes 19 and 80 at the proper instants. The outertube 80 is controlled by a switch 83 which is associated with the cam 55 as shown best in Figure 17. Upon each rotation of the shaft 9 and, therefore, of the sleeve 54, the cam 55 strikes the pivoted contact arm 84 of the switch 83 which is carried on the upper surface of the standard 3, Upon contact of cam 55 with contact 84, such contact is separated from the fixed contact 85 which controls a circuit in which the contacts 84 and 85 are connected in order to cause flashing of the outer tube 80. The flash of this tube will be visible through the opening 82 in the dial as shown in Figures 6 and '7. Thus, a flash of this tube will occur during each revolution of the shaft 9 and in the same relative position so that it will appear as a continuous light at that particular angular position for indicating the location of the force center of the controllable weights. The. inner tube 19 is controlled by pick-up switches 88 each of which is positioned at one edge of the standards 2 or 3 as shown best in Figure 17. Each of the switches 86 comprises a pivoted contact member 81 and an associated contact member 88. When the plate I2 of the associated bearing structure moves outwardly adjacent switch 86, it swings contact 8'! about its pivot and away from contact 88. Separation of these contacts will control the circuit in which they are connected in order to cause flashing of the inner tube 19. The flash of this tube will be visible through the opening 8|, as shown in Figures 6 and 7, and Willoccur during each revolution of the shaft 9 as long as the rotor carried by the shaft is out of balance. Thus, there will appear a constant light at a fixed angular position on the dial 14 indicating the angular position of the effect of the unbalanced weight in the rotor. Furthermore, the comparison of the position of the unbalanced weight of the rotor relative to the position of the force center of the controllable weight 82 will be indicated on the dial as shown in Figure 6. Other conditions which occur during the balancing operation will be indicated by the dial, as illustrated in Figures 7 and 8 and which will be referred to more in detail hereinafter.

The flexible shaft 17 extends to a second instrument 89 on the panel which is a tachometer. The speed of rotation of the motor 4 may be changed by means of a rheostat 90 which is preferably carried by the panel 10. The speed 'of rotation of the shaft can be observed from the tachometer 89 which is desirable since it should be rotated at various speeds during the balancing operation.

The degree of unbalance in the rotor carried by the shaft 9 or, in other words, the degree of vibration produced by such unbalance is indicated by a third instrument 9| carried by the panel 70. This instrument comprises a dial 92 and a pointer 93 which is controlled by variations in current in'an electric circuit in which it is connected in a manner to be described hereinafter.

Variations in current in such circuit are produced by an adjustable core inductor 94 which is illustrated "in Figure 1'7 and is associated {ment of the pointer 91.

with the plate I2. One of these inductors 94 It is provided with a movable core 95 which is engaged by the plate I2 as it moves towards the edge of the standard adjacent which the inductor 94 is positioned. The extent of movement of the core 95 is indicated by movement of the pointer 93. Thus, the extent of movement of the plate I2 in one direction will be indicated.

A fourth instrument 96 is provided on the panel 10 for indicating the'amount of weight required at any given radius which is calibrated from the angular positions of the weights 62. This instrument comprises a dial 91a and an associated pointer 91. The pointer 91 is carried by a shaft 98 which is rotated by means of bevel gears 99. These gears 99 are driven by a flexible shaft I00. The shaft I00 extends to a point adjacent the control lever 64 (Figure 2) and at this end carries a pinion It. This pinion I0! meshes with a rack I02 carried by an arm secured to the lever 84. It will be apparent that swinging of lever 64 about the pivot 65 will result inrotation of shaft I00 and consequently move- Since movement of the lever 64 moves sleeve 54' and thereby adjusts the weights 62, the dial 91a can be calibrated to indicate, in cooperation with pointer 91, the effective weight produced by weights 62.

The main control switch I03 for controlling the electric circuit of the machine is carried by the support 4'! (Figure 2) adjacent the control lever 64. This switch comprises a contact-carrying plate I04 and a movable lever I05.

In order to indicate on the rotor the point where the weight correction should be applied, we provide means for projecting narrow light beams on such point after each balancing operation has been completed. Two lights I06 and I01a are provided for this purpose and are carried within the upper section of the rotor guard 32 at opposite edges thereof and are adapted to project beams on the periphery and adjacent side surfaces of the rotor. These light beams will indicate where the weights are to beapplied to bring the rotor into single plane balance. For indicating where the weights are to be applied on the rotor to overcome couple unbalance, an additional light I01, for use with light I0la, is mounted on the arm I01b carried by standard 3 from light mm but on the opposite side of the rotor. The lights I01 and I0'Ia are adapted to project beams on the periphery of the rotor 180 apart and on adjacent but opposite side surfaces. As will be explained later, independent circuits are provided for controlling the lights I06 and I01a and the lights I01 and MM.

by a screw I09. This disc I08 is provided with a V-shaped notch I I0 on its peripheral edge which is always in radical alignment with the cam portion 55. The opposite sides of this notch carried contact plates II I and H2. The contact I I2 is grounded while the contact I I I is connected to a third contact H3 carried on the side of the disc. At the proper instant, a contact roller II4 will enter the notch H0 (Figure 12) and make the circuit between contacts III and H2. At

1i the same time, a contact roller II will engage the contact H3 and make the circuit at this point. These various contacts, as will later appear, are connected in the circuits for the lights I06, I01 and 101a. v The contact roller H4 is carried on the outer end of an arm I I6 of insulating material which is disposed substantially tangential to the disc I08. This arm IIB is pivoted at its opposite end, as at II1, to an upstanding support II8. This support I I8 is mounted on the upper end of the standard 3 by means of the bolts II9 (Figure 3). The contact roller I I5 is carried by a flexible arm I20 made of conducting material. This arm I20 is resilient and normally extends downwardly. It is attached to the arm H6 and is in diverging relationship thereto. 7 Normally the arm I I6 and the associated arm I20 are lifted upwardly by means of a spring I2I attached to the arm H6 and to a superimposed horizontal arm I22 forming a part of the support H8. 7 However, a solenoid I23 is provided fo pulling the arm II6 downwardly when the solenoid is energized. This solenoid is supported below the arm II6 by a supporting bracket I24 which is attached to the upstanding support H8. The upper end of the core pin I25 of the solenoid is pivotally connected to the arm II6. H

Normally the disc I08 will rotate with the shaft 0 and associated parts without the rollers I I4 and H5 making contact with their respective contacts carried by the disc I08. However, as will later appear, when the balancing operation is completed, the solenoid I23 will be energized pulling the arm I I6 andassociated arm I20 downwardly, This will cause the roller II4 to contact with the peripheral edge of the disc I08. If the entirebalancing assembly including the rotor carried thereby is now rotated manually, the .roller H4 will eventually enter into the notch III] and at the same time the roller I I5 will engage the cam type contact II3. ,This will complete the circuit to eitherthe lights I06 and I01a or the lights I01 and 101a which will project beams on the rotor to indicate where the weight correction should be made.

In Figure 33, we have illustrated the electric circuit of our machine. The main lines I26 and I21 1ead from a suitable source of power and are controlled by a switch I28 which is preferably located on panel 10 (Figure 4). The line I26 is connected to the rheostat 90 by line I26a and a -line I261) leads from the rheostat to the motor 4 while the line I21 is connected directly to the motor. Connected in series in the line I26 are the contacts 32a and 32b of the safety switch associated with the rotor guard 32. Connected in parallel with the lines I26 and I21 by the lines I29 and I30 is a transformer I3I, the secondary of which is provided with a ground I32 and with a positive I33 which is connected to a line I34. The line I34 is connected at one end to contact I35 of group I of contacts of the main control switch I03. It will be noted that this switch is provided with separate groups, I, II, III and IV of contacts, which are carried by plate I04 (Figure 2), and that the control lever I05 may be selectively moved into association with any one of these groups. The line I34 leads to the primary of a transformer I36 and then to the contact I35b of switch I03. The secondary of transformer I36 is provided with a ground I31 and is connected by a line I38 to the tube 19 of instrument 13 which is provided with a ground I39. The other tube 80 is provided with a ground states I40 and with a line I4I which leads to the sec: ondary of a transformer I42 which is provided with a ground I43. The primary of this transformer is connected in 'a line I44 which is connected to line I34 and to terminal I45 'atth'e pivoted end of lever I05. A line I46 leads from the instrument 9|, through inductor 94, associated with bearing II, to the contact I35a of group I of the switch contacts. The inductor '84, associated with bearing I0, is interposed in 'a line I41 which is connected to line I46 and which leads to a contact I482; of group III of contacts of switch I03. The locking solenoid 25, associ ated with bearing I0, is provided with a ground I49 and with a line I50 which is connected to line I41. The locking solenoid 25, associated with bearing II, is provided with a ground I 5I and with a line I52 which connects it to line I46. The solenoid I23 which controls the circuits for the lights I06, I01 and I01a is provided with a ground I53 and with a line I54 which leads to contact I60c of group IV of the contacts of switch I03. The arm II6 associated with solenoid I23 is of insulating material, as previously indicated, and carries contact II4 which cooperates with contacts III and H2. Contact H2 is provided with a ground I56 while contact I I I is connected by wire I51 to cam contact II3. Arm I20, carrying contact H5, is connected by wire I58 to the wire I54. In this line I58 the light [01a is interposed. The light I01 is interposed in a branch line I59 which leads from line I58 to contact I60a of group IV of the switch contacts. The light I06 is interposed in a line I6I which leads from the line I58 to a contact I680 of group II of the switch contacts. The contact 88 of switch 86, associated with bearing I0, is provided with a ground I63 while the contact 81 thereof is connected by line I64 to contact I480 of switch "I03. Similarly, the contact 88 of switch 86, associated with bearing II, is provided with a ground I66 and the contact 81 thereof is connected by a line I61 to a contact I350 of group I of the contacts of switch I03. The contact 85 of switch 83, associated with cam 55, is connected by wire I60 to contact I35d and contact I48d of main control switch I03. The contact arm 84 is provided with a ground I10. In the switch I03 the contacts I60, I48, I68, I35 andI68b are connected together in series by a wire I12. Contact I35 is connected to contact I681) by wire I12a. The contact I48 is connected to contact I601) -by wire I13. The contacts 168a and I600 are connected together by a line I14. The contact I35b is connected to contact I48b by a wire I15, which is also connected to the primary of transformer I36. The lever I05 of switch I03 has its contact I45 connected by wire I16 to contact I11d. The contacts H10 and H119, carried by the lever, are connected together by wire I18 while the contacts I11a and I11 thereof are connected together by wire I19. ,7

Whenever switch I28 is closed, the circuit to the motor 4 is completed, provided the rotor guard 32 is in position and the contacts 32a and 32b of the safety switch associated therewith are engaged. The speed of rotation of the motor can be varied by adjusting the rheostat and it can be completely stopped by such adjustment. With the lever I05 of switch I03 in the position shown in Figure 33, the circuits to all the other electrically operated parts of the machine are broken. Assuming that lever I05 is moved into contact with group I of the contacts of switch I 03, which will be the position it occupies in the contact 13' single plane balancing operation, the circuits, in addition to the motor circuit, will be made as follows: From main lines I26 and I27, through lines I29 and I39 to transformer I3I grounded by line I32, through lines I33 and I34 to contact I35, contacts I77, wire I79, contact I77a, contact I35a, wire I46, to locking solenoid 25 associated with bearing II and grounded at I5I, so as to engage such solenoid and unlock this bearing to permit oscillation 0r vibration of the right-hand end (on the operators left) of shaft 9. Current also continues on through inductor 94 associated with bearing II, being varied by the position of core 95, through line I46 to instrument 9I which will indicate the extent of vibration of the plate I2 of bearing I I. The contact 87 of switch 86, which is associated with bearing II, will be intermittently separated from grounded contact 88, if the shaft is vibrating. The circuit from contact 87 will continue through wire I 67 to contact I350, I770, wire I78, contact l77b, contact I35b, wire I75 to transformer I36 grounded at I37, and then through line I38 to inner light tube 79, of instrument 73, which is grounded at I39. Thus, tube 79' will be illuminated at those intervals when the contacts 87 and 88 of the switch 86 are separated. Since the associated unlocking solenoid 25 is energized the plate I2 of the bearing II is unlocked and reciprocation of such plate is permitted so that the switch 86 is intermittently actuated to flash the tube light 79. Current will also flow from line I34, through line I44, through transformer I42 to the outer light tube 89 of instrument 73 and then into ground I49. The circuit to this tube 89 will be intermittently broken by actuation of switch 83 by means of cam 55 which intermittently separates grounded contacts 84 and contact 85 thereof, contact 85 being connected by wire I69 to contact Id, which engages contact 177d, of lever I95, that is connected by wire I76 to terminal I to which wire I44 is also connected. Thus, with lever I95 in association with group I of the contacts of switch I93, the solenoid 25, switch 86, inductor 94 and switch 83, all of which are associated with bearing II, are connected in the circuit. These will actuate the instruments 73 and 9|, the instrument 89 being actuated by a direct drive from the motor 4. Solenoid I23 and the lights I96, I97 and I97a will not receive current with lever I95 in this position. The instrument 96, as previously indicated, will be actuated by movement of control lever 64 in adjusting the weights 62.

When lever I95 is moved into association with group II of the contacts, which will be the position it occupies after the rotor has been brought into single plane running balance, so as to energize lights I96 and I 97a whichwill indicate where the weight correction is to be made, the circuits will be as follows: From main lines I26 and I27, through lines I29 and I39 to transformer I3I, through lines I33 and I34 to contact I35, and through wires I72a to contacts I68 and I68b. Contact I68 is engaged with contact I77 and the current will flow through wire I79, contact I 770. which is engaged with contact I 68a, wire I74, wire I54 to solenoid I23 which will be energized and will pull arm I I 6 down so that roller contact II 4 will contact disc I98. If disc I98 is rotated sufiiciently, by rotating the rotor assembly, contact II4 enters notch H9 and contact II5 strikes contact H3, thereby completing the, circuit from line I58 to ground I56 and resulting in lighting bulb I97a and also in lighting bulb I96 which is connected to line I6I that runs to contact I68c. Con tact I66c is in engagement with contact I77c which is connected by wire I78 to contact I77b that is engaged with contact I68b, which is connected to the main line, as previously described. Thus, in this position of lever I95, only the circuits for bulbs I96 and I97a and for solenoid I23 are energized.

When lever I95 is moved into association with group III of the contacts, which will be the position it occupies in the couple balancing operation, the circuits will be made as follows: From main lines I26 and I27, through lines I29 and I39 to transformer I3I, through lines I33 and I34 to contact I 35 and through wire I72 to contact I48 which is in engagement with contact I77 that is connected by wire I79 to contact I77a which is in engagement with contact I48a that is connected to line I47. The current passes through line I47 to inductor 94, associated with bearing I9, which is connected to line I46 that leads to extent of vibration instrument 9|. Line I59, which leads to grounded unlocking solenoid 25, associated with hearing III, also receives current from line I47 so that the plate I2 of this bearing will be unlocked and will be permitted to reciprocate, if

the rotor is out of balance. The contact 87 of switch 86, which is associated with bearing I9, will be intermittently separated from grounded contact 86, if the plate II. of the bearing is reciprocating. The circuit from contact 87 will continue through line I64 to contact I480. that engages contact I770, connected by wire I78 to contact I776 which is in engagement with contact I 481). Contact I461? is connected by line I75 to the primary of transformer I36, the secondary of which is connected by line I38 to the grounded inner light tube 79 of instrument 73. Thus, tube 79 will be illuminated at those intervals when the contacts 87 and88 of the switch 86 are separated. Since the associated unlocking solenoid 25 is energized the plate I2 of bearing I9 is unlocked and reciprocation of such plate is permitted so that the switch 86 is intermittently actuated to flash the tube light 79. Current will also flow from line I34, through line I44 to the transformer I42, line I4! to the outer light tube 89 and then into ground I46. The circuit to this tube 86 will be intermittently broken by means 'of cam 55 actuating switch 83 which is connected to line I69 that leads to contact I35 and then to contact I48d which is in engagement with contact I77d that is connected by wire I76 to terminal I46 which is connected to line 344. Thus, with lever I65 in association with group III of the contacts of switch I the solenoid 25, switch 86, and inductor 94, all of which are associated has been overcome so as to energize lights I67 and mm which will indicate where the weight correction is to be made, the circuits will be as follows: From main lines I26 and IN, through lines I29 and I 39 to transformer I3I, through lines I39 and I34 to contact I35 and through wires I72 and I73 to contacts I69 and I692). Contact I69 is in engagement with contact I77 and the current will flow through wire I79, contact. Illa,

which is in engagement with contact 469a, wire 3 59 and wire P58 to contactsarm 12a, associated with W8, which cam when properly rotated, as previously indicated, will ground the circuits in which the bulbs lid-i and [bid are connected. This =ci-rcuit also includes wire 154 that connects to solenoid i 23 which will be energized since line I54 connects to contact I660 thatis in engagement with contact llic which is connected by wire 118 to contact ll'ib that is in engagement with contact [69b which is connected to the source'of current as previously indicated. Thus, in this position of lever I95, only the circuits for bulbs it! and i'iila and for solenoid !23 are energized, the circuit for the bulbs being completed after cam disc 198 is rotated to ground such circuits, in the manner previously described.

In Figures 36 to 40, inclusive, we have provided several diagrams which illustrate the theories relating to unbalanced forces in a rotor and the manner in which our method and machine is used'to balance the rotor. Rotors may, as shown in Figures 36 and 37, be out of balance because of unbalanced radial force or, in other words, be-

cause the rotor is heavier in one radial direction than it is in an opposite radial direction as shown by the arrow a inFigures 36 and 37. This unbalance may be in any plane at right angles to the axis and along such axis, it being shown adjacent the left-hand side in Figure 37, although in the initial balancing operation the rotor is considered as being a'single plane. This is common in static balancing where the only object is to pivot (3), if the rotor is rotated. The shaft will tend to oscillate in a cone-shape path, as shown by dash lines in Figure 38, if the pivot 85 is universal, with its at and the further away from pivot therotor'is located, the'more effective will be the unbalanced weight in the rotor in oscillating the shaft. However, the pivot 69 may be located at various distances from the rotor, as indicated by the s in Figure 38. To overcome this unbalanced condition, we apply an equal and opposite radial force, as indicated by the arrow h, under running conditions of the rotor and this will stop oscillation or vibration of the shaft. The opposite force b is applied evenly distributed across the width of the rotor.

Although the rotor is thus balanced insofar as radial force is concerned, if the forces a and b are not in the same radial plane, there will be a couple or axial moment unbalance. Therefore, to overcome this couple unbalance, the shaft 8 is pivoted for oscillation or vibration about the pivot O which is preferably located as close as possible to the center of gravity of the rotor, as shown in Figure 39, and much closer than the pivot 22). The unbalanced couple or axial moments will cause gyration of both ends of the shaft 3 about the pivot 0 if it is a universal pivot and if the rotor is rotated, such ends describing coneshapepaths, as indicated by dotted lines in Figure 39, with their apexes at the pivot 0. Although, it is preferred that the pivot 0 be close However, we a to the center of gravity of rotor M, it may be located at different distances therefrom in either direction as indicated by the positions of the several Os in Figure 39. To stop oscillation or, in other words, to bring the rotor into balance, it :is necessary to bring the force b in the same plane as force a, as indicated by a comparison of Fig ures 39 and 40.

The machine which we have described, will bring the rotor =M into balance in accordance with the above-discussed principles. The rotor M will be mounted on the shaft 9 by means of the cone-shape clamping members 39 and 3|. The weights '62 are set in neutral position (180 degrees apart), as illustrated in Figure 18, which is accomplished by swinging the hand lever 64 (Figure 2), the position of the weights being indicated by'instrumentfit (Figure 4). The lever 4-95 of main-control switch 193 is moved to position I (Figure 33). This will unlock the bearing 41 without-disturbing bearing l0. This also connects pickup switch'86,and inductor 94, associated with bearing II, and cam switch 83 in the circuit. The motor is started by means of switch 428, provided rotor guard 32 is closed, so as to drive the shaft 9. If the rotor is out of balance, the conditions illustrated in Figures 36 to 38 will be present, except that vibration or oscillation of shaft?) will be confined to a horizontal plane. It will be'noted from Figure 18 that the-weights 62 willeach be spaced 90 degrees from the cam 55 and that notch H0 in disc I08 is in radial alignment with the cam. As rotation starts cam '55 actuates the switch 83 which flashes the outer light tube -80 of instrument 13, indicating the angular position of the forcecenter ofthe weights 62 :relative to shaft 9. As previously indicated, this :fiash'will'appean-as shown in Figures 6 and -'7, asacontinuous light through opening 82 of rotating dial T4 at that'particular angular position. Speed is gradually increased, it'being indicatedb-y instrument 89, until oscillation or vibrationof shaft '9 about bearing IE), as shown in Figure 19, occurs which will be picked up by switch-88, associated with bearing H, and which will be indicated by flashing the inner light tube -19 --which "will appear as a continuous light through-opening 8| at a particular angular position. Thisshows the positionof the excess weight in the rotorMrelative to'the force center of the weights 62. The degree of unbalance is indicated bythe-instrument 9| which is actuated-by inductorQ-i thatis associated with bearing H. In Figures 18 to 23, the unbalanced weight in the -rotor-M- is indicated at W.

The-instrument 13 now shows a flash at some angular position in the rotating dial T4 through inner openingvSl indicating the location of the unbalanced weight W in rotor'M relative to the force center of weights '62 which is indicated by a flash appearing at some angular position in thetrotatingdial 'i ithrough outer opening 82. The entire weight assembly, without disturbing 'the relative positions of weights 62, as indicated 65 *by dash lines in Figures 18 and 23, is now rotated around theshaft '9 by operating control lever45. This brings the cam 55 in diametrical alignment-with the excess weight W in the rotor -'and-this condition will be indicated, as shown in Figure 7, when the two flashes on instrument 13 appear-t0 be inradial alignment. The vector V of force produced by the weights-62 is now degrees from the unbalanced weight W in rotor a -indicated by dotted lines inFigures 18 17 relative to each other from their original position (180 degrees apart) towards each other in the example shown, by operating the control lever =64, producing the vector V of forces along the center line of cam 55. This weight force is increased by moving the weights towards each other, and as it is so increased the degree of vibration of the shaft will decrease as indicated by a comparison of Figures 19, 20 and 21, until oscillation of the shaft ceases (Figure 22) which will be indicated by instrument 9| (Figure 4). At this time, the inner flash on instrument 13 (Figure 8) will not appear.

The circuit to the motor 4 is broken by moving lever 95) of the rheostatand rotation of shaft 9 can now be stopped by using brake 4a. The lever I of switch 1113 is now swung into position II. As previously indicated, in this position, the solenoid 523 will be energized and the circuits to lights I as and illla will be so set up that if the shaft and rotor are rotated manually until contact roller H41 of arm HG enters notch H0 of disc Hill, the circuits to the lights H and Hila are completed so that they cast radially disposed lines of light on opposite sides of the rotor M and a transverse line of light on the periphery thereof, indicating exactly where the weights should be applied to the rotor to bring it into single plane balance. The exact amount of weight to be added (or removed) is shown on the dial of indicator 96 which may be calibrated in ounce-inches for the particular radial position of the weights. The exact amount of weight is now added to the exact angular point indicated (or removed from a diametrically opposed point) and is preferably evenly distributed between the planes or side surfaces of the rotor. The rotor will now be in single plane balance.

With single plane balancing of the rotor thus accomplished, the next step will be to neutralize the unbalanced couple in the rotor. The weights 52 are again set in neutral position (180- degrees apart), as illustrated by full lines in Figure 30, by means of hand lever t4 and as indicated by instrument 95. The lever I05 of main contact switch "i3 is now moved to position III. This will unlock the bearing l6 and permit locking of bearing H and also connects pickup switch 86 and inductor 94, associated with hearing It}, and cam switch 83 in the circuit. The motor is started by means of lever 90, provided rotor guard 32 is closed, so as to drive the shaft 9. If an unbalanced couple is present, for example the unbalanced weights A and B which in this exam ple are at opposite sides of the rotor, but may be at different planes within the rotor, the conditions illustrated in Figures 39 and will be pres ent, except that vibration or oscillation of shaft 9 will again be confined to a horizontal plane. Because the rotor has previously been brought into single plane balance it will be known that the couple weights or forces A and B are 180 apart. As rotation of shaft 9 starts, the cam will actuate switch 83. producing the outer flash on instrument F3, indicating the angular position of the force center of the weights 62 relative to shaft 9. Speed is gradually increased and oscillation of shaft 9 about bearing H, as shown in Figure 24, occurs and will be picked up by the switch 8% associated with bearing it which will produce the inner flash on instrument E3. The degree of unbalance will be indicated by instrument 9i actuated by pickup 94 associated with bearing it. The instrument l3 now shows a flash through outer window 82 at some angular posion the dial of indicator 96.

18 tionin the rotating dial 74 indicating the angular location of the force vector K (Figures 28 to 31) relative to the force vector produced by the unbalanced couple in rotor M which is indicated by the flash in the inner Window 3|.

The entire weight assembly, without disturbing the relative positions of weights 62, as indicated by dash lines in Figure 30, is now rotated around the shaft 5-) by means of lever $5. This brings the cam 55 in diametrical alignment with the vector K and this condition will be indicated, as shown in Figure 7, when the two flashes on instrument '13 appear to be in radial alignment. The vector Biofforce produced by weights 62 is now in the same diametrical plane as the couple A and B in the rotor M, as shown best in Figure 28. As indicated by dotted lines in Figure 30, the weights 62 are now moved angularly from their original position (180 degrees apart) towards each other in the example shown, by means of lever 65, and the vector K will still be along the center line of cam 55. This weight force is increased by moving the weights towards each other, and as it is so increased the degree of vibration of the shaft will decrease as indicated by a comparison of Figures 24 to 26, until oscillation of the shaft ceases (Figure 27) which will be indicated by instrument 91 (Figure 4) and. also instrument 13 as shown in Figure 8 since the inner flash will not appear.

The motor i is now de-energized by lever and rotation of the shaft can be stopped by using brake Ea. The lever of switch )3 is now swung into position IV. As previously indicated, in this position, the solenoid I23 will be energized and the circuits to the lights l0! and [01a will be set up so that if the shaft and rotor are rotated manually until contact roller H4 enters notch till of disc E98, the lights it]? and 11a will goon and will project radial lines of light on opposite sides of the rotor, degrees apart and on opposite sides to the location of the forces A and B. The exact amount of weight to be added at each side is one-half the amount shown After this weight correction is made, the rotor will be in complete running balance.

The formula by means of which the adjustment of weights 62 overcomes the unbalanced couple is indicated in Figure 32 and its application to the rotor and weights is indicated in Figures 28 to 31. The vector of the force produced by weights 62 is K and its radius is Z. E. is the moment arm of force K about the pivot of bearing H. B is one force of the couple (weight in ounces) and Y is the radius of B. A is the other force of the couple and X is its radius. G is the distance from the inner force A to the pivot point and H and F are each one-half the distance between A and B. Thus, magnitude of the force exerted by weights 52 is KZ at moment arm E and by adjusting the weights can be caused to equal the force produced by BY at lever arm G-l-H-l-F less the force AX at lever arm G, or the force exerted by the couple and tending to oscillate the shaft about pivot l l.

With reference to Figures 34 and 35, we have illustrated a rotor of the type affected by air resistance upon rotation. This rotor is shown as being an aircraft propeller or air screw and is indicatedby the reference character N. It will be understood that if such a rotor is rotated at high speed and any unbalance appears, two factors might be involved in such unbalanced condition, that is, weight unbalance and aerody- 19 namic unbalance. To eliminate the latter factor in the balancing operations according to our method, we enclose the rotor N in a cylindrical housing I95. This housing I95 includes a removable closure l96 which may be attached to the main part of the housing by bolts lEil'. The housing I95 may be keyed to the shaft 90 for rotation therewith by a transverse bolt !98 extending through the hub I99 of the housing and through the shaft. It will be apparent that if the rotor N is mounted on the shaft in the previously described manner, the housing I95 is closed and the shaft is rotated, the only factor which will tend to produce oscillation of the shaft will be weight unbalance in rotor N, it being understood that the housing is perfectly balanced. The balancing operations can then be carried out in the previousl described manner according to our invention.

It will be apparent from the above description that we have provided a novel method and apparatus for balancing a body to be rotated, According to our invention, a body can be balanced accurately and consistently at all speeds of rotation in such a manner as to overcome both radial and axial moments, that is, those unbalanced conditions which are referred to in the prior art as static and dynamic unbalances. With our method and machine, the rotor is balanced under conditions simulating actual running conditions to overcome both types of unbalance. The unbalanced conditions are overcome by introducing equal and opposite forces to the unbalanced forces in the rotor while it is being rotated. With our machine, the effect of lag between the instant of vibration and the indication of pickup of such vibration is eliminated because the rotor is not only tested while being rotated on our machine but is actually brought into balance during such rotation. With our machine, the rotor mounted thereon can be brought into balance with ease and accuracy. The machine is so simple and easy to operate that a highly skilled operator is not required and calibration by the operator is not required since the location and amount of weight correction necessary to bring the rotor into balance will be definitely indicated by instruments on the machine.

'Various other advantages will be apparent from the drawings, the preceding description and the following claims.

Having thus described our invention, what we claim is:

1. The method of balancing a rotor which comprises rotating the rotor to be balanced about the axis upon which it is designed to rotate and causing such axis to oscillate freely, if the rotor is unbalanced, about a point spaced remotely axially from the rotor so as to cause unbalanced radial force only in the rotor to exert a substantial effect to produce such oscillation, bringing the rotor into single plane balance while rotating, as indicated by the decrease and ultimate ceasing of the oscillation of the axis of the rotor, by setting up a counterbalance force at a location axially between the said point and the said rotor but closel adjacent to the rotor and which acts in a plane at right angles to said axis and at an angular position around the axis, where it overcomes the said single plane unbalance, making the weight correction on the rotor, as indicated by the angular position and amount of the force, then, with the rotor supported in its original position, rotating it about its own axis again and causing such axis to oscillate freely. if unbalanced axial moments are present therein, about a point different from said first point and located axially between the said plane of said force a d said rotor so as to cause the unbalanced axial moments only in the rotor to exert a substantial effect to produce such oscillation, bringing the rotor into couple balance while rotating, as indicated by the decrease and ultimate ceasing of the oscillation of the axis of the rotor, by varyi the angular position of the counterbalance force in the same plane about such axis and its effective value so as to overcome said unbalanced axial moments, and finally making the weight correction on the rotor, as indicated by the adjusted angular position and amount of such force, thereby bringing the rotor into running balance.

2. The method of balancing a rotor which comprise rotating the rotor to be balanced about the axis upon which it is designed to rotate and causing such axis to oscillate freely, if the rotor is unbalanced, about a point spaced remotely axially from the rotor so as to cause unbalanced radial force only in the rotor to exert a substantial effect to produce such oscillation, bringing the rotor into single plane balance while rotating, as indicated by the decrease and ultimate ceasing of the oscillation of the axis of the rotor, by adjusting a plurality of radially acting counterbalance weights both relatively and as a unit about said axis in a plane at right angles to said axis which is located axially between the said point and the said rotor but closely adjacent to said rotor, to angular positions where they overcome the said single plane unbalance, making the weight correction on the rotor, as indicated by the adjusted angular positions and effective amount of the said weights; then, with the rotor supported in its original position, rotating it about its own avis again and causing such axis to oscillate freely, if unbalanced axial moments are present therein, about a point different from said first point and located axially between said plane of said weights and said rotor so as to cause the unbalanced axial moments only in the rotor to exert a substantial effect to produce such oscillation, bringing the rotor into couple balance while rotating, as indicated by the decrease and ultimate ceasing of the oscillation of the axis of the rotor, by varying the angular positions of the same counterbalance weights by adjusting the weights angularly both relatively and as a unit in the same plane about such axis to vary their effect so as to overcome said unbalanced axial moments, and finally making the weight correction on the rotor, as indicated by the adjusted angular position and effective amount of such weights thereby bringing the rotor into running balance.

3. Apparatus for balancing a rotor comprising a supporting structure, a shaft carried by said supporting structure, means for mounting the rotor on said shaft at a selected position axially thereof for rotation about the axis upon which it is designed to rotate and with such axis corresponding to that of the shaft, means for sup-- porting said shaft on said supporting structure for selective oscillation, if the rotor mounted thereon is unbalanced, about two different points spaced axially along said shaft to one side of and different distances from said mounting means for the rotor, and a counterbalance Weight unit supported on said shaft at an axial point between said points about which the shaft may oscillate for rotation with the shaft, said counterbalance weight unit including a counterbalance weight adjustable angularly about the axis of said shaft in a plane at right angles thereto.

4. Apparatus for balancing a rotor comprising a supporting structure, a shaft carried on said supporting structure, means for mounting the rotor on said shaft at a selected position axially thereof with the axis upon which it is designed to rotate corresponding to that of the shaft, means for supporting said shaft on said supporting structure for rotation and for selective oscillation, if the rotor mounted thereon is unbalanced, about two different points spaced axially along said shaft to one side of and different distances from said mounting means for the rotor, and a counterbalance weight unit supported on said shaft for rotation therewith at an axial point between said points about which the shaft may oscillate, said counterbalance weight including a plurality of weights angularly adjustable relative to each other and as a unit about the axis of said shaft in a plane at right angles thereto.

5. Apparatus according to claim 4 wherein the means for supporting said shaft includes means for confining the oscillation of said shaft in a single plane through the axis of the shaft;

6. Apparatus according to claim 5 including indicating means operatively connected to said adjustable weights for indicating the relatively adjusted angular positions of the weights, indicating means operatively connected to said weights to indicate the position of said weights as a unit about the axis of said shaft, and indicating means operatively connected to said shaft for picking up oscillation of said shaft when it is oscillating about either of said points.

'7. Apparatus for balancing a rotor comprising a supporting structure, a shaft carried on said supporting structure, bearing units on said supporting structure spaced axially of the shaft for supporting said shaft for rotation about its axis, means for driving said shaft, means for mounting a rotor on the shaft with the axis upon which it is designed to rotate coinciding with that of the shaft for rotation therewith and located axially to one side of both of said bearing units, each of said bearing units including a pivot so that the Shaft supported thereby can swing in the plane of its axis if the rotor mounted on the shaft is unbalanced, means carried by the supporting structure for selecting either of said bearings to permit swinging movement of the shaft about the pivot thereof, a plurality of counterbalance weights carried by said shaft in a single plane at right angles to the axis of the shaft for rotation therewith at a point axially between said bearing units, means carried by said shaft for adjusting said weights about said shaft angularly relative to each other in said plane, and additional means carried by said shaft for adjusting said weights as a unit about said shaft without disturbing their relative angular positions.

8. Apparatus according to claim 7 including indicating means operatively connected to said weight adjusting means for indicating the relatively adjusted angular positions of the weights, indicating means operatively connected to said weight adjusting means to indicate the position of said weights as a unit about the axis of said shaft, and means carried by the supporting st1'uc-' ture at each of said bearings for picking up oscillation of said shaft when it is oscillating about either of said pivot points.

9. Apparatus for balancing a rotor comprising a supporting structure, a shaft carried on said supporting structure, bearing units onsaid supporting structure spaced axially of the shaft for supporting said shaft for rotation about its axis, means for driving said shaft, means for mounting a rotor on the shaft with the axis upon which it is designed to rotate coinciding with that of the shaft for rotation therewith and located axially to one side of both of said bearing units, each of said bearing units including a reciprocable member for supporting the shaft for bodily swinging movement in the plane of its axis if the rotor mounted on the shaft is unbalanced, locking means at each of said bearing units for locking said reciprocable member so as to prevent movement thereof, control means on the supporting structure for selectively actuating either of said locking means, each of said bearing units also including a bearing member which is pivoted to said reciprocable member, a plu-' rality of counterbalance weights carried by said shaft for rotation therewith at a point axially between said bearing units, means carried by said shaft for adjusting said weights about said shaft angularly relative to each other in a single plane at right angles to said shaft, and additional means carried by said shaft for adjusting said weights as a unit about said shaft without disturbing their relative angular positions, both; of said last-named means being operable during; rotation of the shaft.

10. Apparatus according to claim 9 wherein said counterbalance weights are carried by armsextending radially from said shaft, and wherein. said means adjusting said weights includes means for supportin said arms on the shaft for movement towards and away from each other and for movement as a unit about the shaft, means connected to said arms for adjusting said arms towards and away from each other, additional means connected to said arms for moving said arms as a unit about the shaft, and control -means for operating both of said last-named means from a remote point on the supporting structure which is operable during rotation of the shaft.

l1. Apparatusaccording to claim 10 comprising indicating means on the supporting structure operatively connected to said radially extending arms to indicate the relative positions of said arms.

12. Apparatus according to claim 11 comprising indicating means on the supporting structure operatively connected to said radially extending arms to indicate the position of said arms as a unit around said shaft.

13. Apparatus according to claim 12 compris ing means carried by said supporting structure at each bearing unit for contact by said reciprocable supporting member for indicating when such member is reciprocating.

14. Apparatus according to claim 13 wherein a movable member is carried by the supporting structure at each bearing unit and is connected to said reciprocable member so that it will be moved thereby, and an indicator connected to said movable member for operation thereby for indicating the extent of movement of said reciprocable member.

15. Apparatus according to claim 14 wherein said indicating means operatively connected to said radial rms comprises a cam, means for sup-. 

